Many crops, grains and other agricultural products contain pests, parasites, insects or other vermin, such as for example borers, lice, ticks, fleas or termites. It is best to treat such bulk materials in situ so that multiple handling in a further treatment process is not required and before the goods leave their geographic region of origin to prevent the spread of insects and vermin.
Fumigation devices for bulk materials are known in the art that involve placement of a heavy, impervious blanket or other covering article over the materials followed by subsequent addition of toxic gas flow under the blanket to fumigate the covered goods. Current methods of fumigation under blankets are crude, ineffective at fully eliminating insect infestation since no mixing of gases with bulk materials can occur, and highly dangerous from an occupational health standpoint since the gases used for effective fumigation are extremely toxic. Atmospheric discharges of fumigant gases such as methyl bromide are highly undesirable also because this gas is an ozone depleting substance.
In JP2303442 a fumigation system is described which teaches venting the gaseous fumigant (or incinerating and then venting to atmosphere the gaseous products of the so-incinerated fumigant) once it has been exhausted or extracted from a fumigation chamber. This document teaches that the way to deal with fumigant or fumigant by-products is by venting to atmosphere, whether by fan extractor located on the fumigation container or coupled to such a device on an adjacent mobile vehicle. Once again such atmospheric discharges are undesirable from a pollution and occupational health standpoint.